Practice Sheet 1
For each of the following, write and label the oxidation and reduction half reaction equations. Ignore spectator ions.
(b) Cl2(g) + NaBr(aq) à NaCl(aq) + Br2(l)
(c) HCl (aq) + Mg (s) à MgCl2 (aq) + H2 (g)
(d) Mg(s) + Br2(l) à MgBr2(s)
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Writing Half Reactions for Complex Redox Reactions
Most metals and nonmetals have relatively simple half­reaction equations,
polyatomic ions and molecular compounds undergo more complicated oxidation and reduction processes. In most of these processes, the reaction takes place in an aqueous
solution that is acidic Example 1
Nitrous acid can be reduced in an acidic solution to form nitrogen monoxide gas. What is the reduction half­reaction for nitrous acid?
Example 2
Chlorine is converted to perchlorate ions in an acidic solution. Write the half­reaction equation. Is this half­reaction an oxidation or a reduction?
Example:
Write the reducon, oxidaon and net reacon for the incomplete redox reacon below that occurs in acidic condions
HNO2(aq) + In +(aq) à NO(g) + In 3+ (aq) .
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Practice Sheet 2
1. Complete the following half reactions and classify them as a oxidation or reduction
a. dinitrogen tetraoxide reacts to form nitrogen gas in an acidic solution
b. chromium (III) ions are converted to dichromate ions in an acidic solution
2. Balance each of the following skeleton reactions by creating the oxidation and reduction half reactions and then combining them to get the complete redox reaction. Be sure to label each half reaction as oxidation or reduction.
a. TiO2(s) + V2+(aq) àTi(s) + V3+(aq)
b. BrO3‐(aq) + H2C2O4(aq) àBr­(aq) + CO2(g)
c. OF2(aq) + I­(aq) àF­(aq) + I3­(aq)
.
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